Rare U.S. ferret marks 30-year comeback

The black-footed ferret was declared extinct in 1979, two years before a small band of survivors turned up in Wyoming. And now, after 30 years of rehab, the species is one of America's top conservation success stories.

Thirty years ago this week, Lucille Hogg and her dog accidentally brought an extinct species back from the grave.

The black-footed ferret — North America's only ferret — was officially declared extinct in 1979, after the last-known colony died five years earlier. But in late September 1981, Hogg's dog brought a dead black-footed ferret to her door in Meeteetse, Wyo., sparking a scientific scramble across the prairie to find more.

The search eventually led to an empty prairie-dog complex nearby, since black-footed ferrets both eat prairie dogs and commandeer their burrows. There, two years into their supposed extinction, the planet's last few dozen black-footed ferrets were found living in a colony that had apparently been isolated since the 1930s. Wildlife officials decided to simply guard and monitor them from afar, a hands-off strategy that seemed to be working as the population grew from 61 in 1982 to 129 in 1984.

But the ferrets weren't as healthy as they looked. Some 20 to 30 generations had transpired during half a century of isolation in Meeteetse, according to a research paper by the Thoreau Institute, and demographic data suggested their genetic diversity had diminished by up to 60 percent. When sylvatic plague hit the colony in 1985, it was almost a fatal blow. Officials dusted the burrows with carbaryl, an insectide to kill the plague-carrying fleas, but the colony still shrunk by 22 percent.

To save the species, biologists removed six ferrets from the wild in October and November of 1985, and then another five adults and two litters in the summer of 1986. The captive population was up to 18 the next spring, and that summer it produced two litters in captivity, totaling eight new kits. It reached 180 by the end of 1990, and in 1991 scientists began releasing black-footed ferrets back into the wild. A rare conservation success story had unfolded in just a decade — and provided a much-needed model for how to save other endangered species.

Now, 30 years after their rediscovery and 20 years after their reintroduction, some 1,000 black-footed ferrets are thought to live across the central U.S., with four self-sustaining populations in South Dakota, Arizona and Wyoming. Zoos in four states and Canada now breed them, and the Smithsonian National Zoo has developed an artificial-insemination technique that has so far produced 139 kits, the Associated Press reports. Scientists are also building a ferret sperm bank to protect their genetic diversity, and five kits have already been reared using frozen sperm. When captive-bred ferrets are ready for the wild, they first spend 30 days in "ferret boot camp" to acclimate them to self-sufficiency, a strategy that reportedly boosts their odds of survival by 10 percent.

Black-footed ferrets will likely always live in the shadow of their glory days, when some 1 million to 6 million lived across the Great Plains, but they at least seem to be past the dark days of 30 years ago. And while they'll never know it, they owe their lives to Lucille Hogg, her dog and countless dedicated conservationists across the country.

In honor of this year's milestone, here's a funny video of a black-footed ferret cavorting around his reclaimed habitat:

And a few photos that show their characteristic blend of charisma and caution: